Oil or gas wells are normally built up by a number of bore holes each normally having steel casings in various sizes, with the largest casing diameter closest to the surface, and smaller sizes with increasing depth of the well. In most oil wells a so-called completion is installed in order to produce oil from certain and desired levels or zones in the well. A completion usually consists of a so called packer device by help of which a production zone could be defined/created, allowing production, e.g. by means of a smaller tube/tubing installed inside the casing and leading up to the surface.
The stresses and wear on the components and tubing used in the completion can be very high, both from a thermal point of view, but also purely mechanical in the form of compressive stresses, wear/erosion and from aggressive chemical environments. It is not uncommon that the tubing over time will become damaged by wear or thermal effects and begins to break or leak.
This leaking problem has to be solved before the production of oil can be resumed in full scale. Repairing the tubing can be done e.g. by pulling all tubing out of the well bore and replace the completion. This is a comprehensive task as the tubing can be very long. In many cases the tubing is also permanently installed in the well bore connected to one or more permanent packers. In such cases the completion often has to be drilled out and be exchanged by new equipment. All this will take a lot of time and the operation as well as the new equipment will be very costly. Substantial production time is also lost.
Consequently, there is a need for a system that can minimize the part of the leaking completion that must be replaced, be easily installed, withstand high temperatures and high mechanical erosion and that can be manufactured and installed at a reasonable cost.